Color reduction of olefin sulfonates

ABSTRACT

The color of an olefin sulfonate is improved by treatment of the olefin prior to sulfonation with minor amounts of sulfur trioxide, slaked lime and bauxite.

[11] 3,719,704 [451 March 6, 1973 COLOR REDUCTION OF OLEFIN SULFONATES [75] Inventor: David M. Marquis, Lafayette, Calif.

[73] Assignee: Cheron Research Company, San

Francisco, Calif.

[22] Filed: May 13, 1970 [21] Appl. No.: 37,041

[52] U.S. Cl. .....260/5l3 R, 260/677 A, 260/677 AD [51] Int. Cl. ..C07c 143/02, C07c 143/16 [58] Field of Search ..260/677 A, 677 AD, 513

[56] References Cited UNITED STATES PATENTS 3,660,472 5/1972 Majima et a1.; ..260/531 R 3,492,343 1/1970 Garner et a1 ..260/513 R 3,481,849 12/ 1969 Beermann et a1 ..260/5 13 R OTHER PUBLICATIONS Smith, Defensive Pub. Search copy of serial No.

848,096, filed 8-6-69, published in 876 0.6. 815, on

7-2870, Defensive Pub. No. T-876,002.

Primary Examiner-Daniel D. Horwitz Attorney-John Stoner, .lr., G. F. Magdeburger, D. L. Hagmann and J. A. Buchanan, Jr.

[5 7] ABSTRACT The color of an olefin sulfonate is improved by treatment of the olefin prior to sulfonation with minor amounts of sulfur trioxide, slaked lime and bauxite.

7 Claims, No Drawings COLOR REDUCTION OF OLEFIN SULFONATES FIELD OF THE INVENTION This invention relates to a method for the production of olefin sulfonates having improved color.

PRIOR ART It is known (see, for example, US. Pat. No. 3,444,191) to manufacture detergent range, i.e., C -C acyclic sulfonates by the reaction of dilute sulfur trioxide with a mono-olefinic alkene hydrocarbon in a liquid phase reaction, particularly by the use of alphaolef'ms (cracked wax olefins) obtained by the non-catalytic cracking of normal paraffinic hydrocarbon feeds at a temperature in the range from about 800F. to 1,200F. A disadvantage experienced in these olefin sulfonations is that the presence of relatively minor amounts of impurities in such cracked wax olefin feeds upon interaction with sulfur trioxide result in a sulfonate product having an unacceptable color. There is consequently a need for an efficient and practical method for treating detergent range cracked wax olefms which renders them satisfactory for use in the sulfur trioxide sulfonation process.

THE INVENTION The color of a sulfonate obtained by the dilute sulfur trioxide sulfonation of a detergent range cracked wax olefin is reduced by a treatment prior to the sulfonation in which:

1 the olefin is contacted with an amount of dilute sulfur trioxide, based upon the weight of the olefin, in the range above about 0.1 and less than about 5 percent;

2 an amount of slaked lime, based upon the sulfur trioxide used, in the range of 0.6 to 1.5 mols per mol of sulfur trioxide is added with mixing to the olefin;

3 an amount of bauxite, based upon the weight of the olefin, in the range from 2 to percent, is also added with mixing to the olefin; and

4 the resulting-mixture of solids is separated from the olefin by filtration.

The foregoing treatment removes in large part the color body precursors ordinarily present in cracked wax olefins.

By dilute sulfur trioxide, as used herein, is meant a gaseous mixture of sulfur trioxide and an inert gas such as air, nitrogen or the like wherein the mol fraction of the sulfur trioxide in the mixture is less than one-fifth, preferably in the range one-twentieth to one one-hundredth.

By a cracked wax olefin, as used herein, is meant by definition olefin obtained by heating a wax feed which is a saturated hydrocarbon mixture containing at least 80 weight percent of straight chain parafiin, wherein the heating is at a temperature in the wax cracking range, i.e., 800-l,200F., with the feed in the vapor phase. Wax cracking is well known in the art (cf US. Pat. 2,172,228).

In the above treatment the temperature of the olefin should be maintained in the range from about 0C. to 60C. Somewhat higher temperatures, as high as about 100C., may be employed, i.e., in the range 0 to 100C. However, as the temperature is increased, the sulfonate color problem is also increased.

The slaked lime provides inorganic base for the neutralization of acid, sulfonic and sulfuric, present in the treated olefin, and it serves together with the generated calcium slat as a locus for the agglomeration into a filterable mass of the sludge resulting from the action of the sulfur trioxide upon the impurities in the olefin. The amount of the lime desirably employed varies depending upon the relative impurity content of the olefin. In general, a satisfactory amount is in the range from about 0.6 to 1.5 mols per mol of sulfur trioxide used in the prior step of the process. A larger relative amount of the lime can be added to the olefin, but such is ordinarily uneconomical.

The solids, slaked lime and bauxite employed herein, should be in particulate form, that is, have a size in the range 20 to 200 mesh for efficient contacting and removal by filtration.

The amount of sulfur trioxide gas required in the pretreatment for a satisfactory reduction in the color of the sulfonate herein varies. Based upon the weight of the olefin to be treated, as little as 0.1 weight percent is beneficial. Usually an amount in the range 0.2 to 4 weight percent is satisfactory. Depending upon the particular olefin treated there appears to be an optimum amount or range of amounts of sulfur trioxide which should be used for the treatment. The use of an amount of sulfur trioxide substantially in excess of the optimum results in the worsening of the sulfonate color rather than the desired improvement. A number of factors appear to be involved including solubilization of sludge, phase separation difficulties and the like. Usually the employment of a relative amount of sulfur trioxide in the range 5-6 weight percent (based upon olefin) will be excessive, i.e., exceeds the optimum value. Thus, an amount of sulfur trioxide greater than about 0.1 and less than about 5-6 weight percent is required for a useful result in the subject process. The preferred amount is in the range from 0.2 to 2.0 percent.

The addition of the bauxite improves the filterabilit of the oil and solids mixture and the color of sulfonate detergent obtainable from the treated olefin. The advantage, in part, appears to be due to the adsorption by the bauxite of polar impurities in the partially sulfonated olefin. Usually about 2-4 weight percent (based upon the olefin) of the bauxite is sufficient for the present purpose. An amount in the range 5-10 percent is ordinarily excessive in terms of economical and efficient usage of treating agent and minimization of olefin losses through mechanical effects such as occlusion, adsorption, and the like.

PREFERRED EMBODIMENT A cracked wax olefin an alpha-olefin mixture of the C -C, range, obtained by thermally cracking a deoiled paraffinic hydrocarbon mixture in the vapor phase at a temperature of 1,000-1,l0OF. and fractionally distilling the resulting product mixture, is given the subject color reducing pretreatment. The olefin is charged into a falling film continuous reaction unit maintained at 30-40C. by an indirect heat exchanger. Concurrently a gaseous mixture of air and sulfur trioxide of the mol ratio to 5, respectively, is contacted with the film of the olefin feed at the rate sufficient for the contacting in parts by weight of 2 parts of sulfur trioxide with parts of the olefin.

The reaction product stream withdrawn from the reactor is then mixed with powdered slaked lime and bauxite in a suitable mixing vessel. For each mol of sulfur trioxide added to the olefin about 1 mol of the lime is added to the mixing vessel and for each 100 parts by weight of the sulfonated olefin about 3 parts of the bauxite are added. The resulting mixture is stirred for a period sufficient to insure efficient contacting of the liquid and solids in the mixture, i.e., for a period of -30 minutes in an ordinary commercial unit. Separation of the solid mixture from the treated olefin is then effected by filtration. The separated and treated olefin has a good color and may be sulfonated in the conventional manner, or preferably, is distilled over solid caustic. When the treated olefin is converted to sulfonate in a conventional process including sulfonation, neutralization, hydrolysis and bleaching, as known in the art, the sulfonate product has a Klett color value which is for all practical purposes the equivalent of the value for sulfonate obtainable from a pure alpha-olefin, i.e., about 65, that is in general about 40-100 Klett numbers below the value obtainable for sulfonates produced from the untreated alpha-olefin under otherwise comparable conditions.

Alternatively, the pretreatment of the olefin may be satisfactorily accomplished in ordinary batch-type systems and, if desired, the full treatment, partial sulfonation and addition of the solids can be carried out in the same vessel.

The olefinic hydrocarbons contemplated as feeds for the process of the invention are obtained by the cracking of paraffins in the vapor phase, as noted above. Olefins so derived having a carbon atom content in the range eight to 24 and higher, in general, are improved by the present treatment. Similarly, individual molecular fractions or distillation cuts from the C t-C range and mixtures thereof are improved.

Representative process feeds suitable for use herein include the C fraction, the C -C fraction, the C -C fraction, and the Gi -C fraction. Alternatively, a broad range fraction, the C -C cut, may be treated and subsequently separated by distillation into molecular mixtures as desired.

In the examples to follow and for comparative purposes herein, a set of standardized conditions were employed for the several steps involved in converting an olefin feed to an olefin sulfonate detergent. These examples are for the purpose of illustration alone and are not to be understood as delimiting the invention.

EXAMPLES A typical C -C a-olefin feed having the molecular distribution:

was used in the comparative examples.

SULFONATIONS A. Continuous sulfonations were run in a falling film reactor comprising a 30.5 cm vertical tube having an internal diameter of 5 mm. Temperature control was maintained by jacketing the tube with a water cooler.

At the upper end of the tube peripheral inlets provided for introduction of the olefin feed and a small central inlet was used for the introduction of a gaseous mixture of sulfur trioxide and nitrogen (5:95, volume ratio, respectively). into the reactor. The olefin feed passed down the reactor walls by a combination of gravity and gas drive flow. In the treatment stage, the feed rates, olefin and gas mixture, were adjusted to yield an olefin to S0; ratio in parts by weight of to' 2. The reaction mixture exiting from the lower end of tube was accumulated in a holding vessel fitted with a stirring device. Average residence times in the reactor tube and holding vessel were about 2 seconds and 3 minutes, respectively.

B. Batch sulfonations were carried out in a turbomixer equipped with a stirrer, a thermometer, reflux condenser and a gas inlet tube. The olefin, 450 g., 2.0 moles, was charged to the reactor and 4.8 g (0.06 mol) of a sulfur trioxide-nitrogen mixture (5:95, volume ratio, respectively) was introduced into the stirred olefin over a period of 40 minutes. The final temperature of the mixture was 30C. At the completion of the sulfonation 3.4 grams (0.06 mol) of calcium oxide and 13.9 g of bauxite (filtrol clay) were added and the mixture was stirred for twenty minutes and filtered. The filtrate was distilled under reduced pressure.

NEUTRALIZATION The olefin sulfonates prepared from the treated olefin aliquots were prepared in the continuous unit as described above, except that the mo] ratio of olefin to sulfur trioxide was about 1 to 1.2, respectively. The free acid in the product mixture was neutralized by ad ding the mixture to a stirred aqueous caustic solution (8 percent NaOH by weight) in an amount sufficient to provide 0.5 mol of the base per mol of sulfur trioxide used in the sulfonation.

HYDROLYSIS The neutralized reaction product mixture was hydrolyzed by heating the mix at a temperature of about C. and a pressure sufficient to maintain the liquid phase. The reaction was complete after a period of 20 minutes.

BLEACHING The hydrolysis product was bleached using sodium hypochlorite in a conventional manner. Thus, the concentration of the hydrolysis product was adjusted by addition of water to yield a 25 weight percent concentration of the sulfonate in water. The diluted solution was then heated to about 50C. and to it was then added sufficient of a 9.2 weight percent solution of the hypochlorite to provide 6.7 mls of the latter per each 100 grams of the diluted hydrolyzed sulfonate solution. After one hour at the 50C. temperature, the heating was discontinued. The color determinations were made using 5 weight percent aqueous solutions of the sulfonate products. The measurements were made in a Klett-Summerson photoelectric colorimeter using a 40 mm cell. The results were as follows:

Essentially, as in Example 3, an olefin feed was treated in continuous mode except that about 5 weight percent, an excess, of sulfur trioxide was used. There was no improvement in the sulfonate color.

From the foregoing it may be seen that the process of the present invention provides a method for markedly improving the color of a cracked wax olefin sulfonate.

Although only specific arrangements and modes of construction and operation of the present invention have been described and illustrated, numerous changes could be made in those arrangements and modes without departing from the spirit of the invention, and all such changes that fall within the scope of the appended claims are intended to be embraced thereby.

I claim:

1. In the process for the manufacture of an olefin sulfonate, the improvement yielding an olefin sulfonate of improved color which comprises treating a cracked wax olefin feed of the C -C molecular weight range by contacting the feed with a gaseous mixture of sulfur trioxide and an inert diluent, said mixture having a mol fraction of sulfur trioxide which is less than one-fifth and said contacting being at a temperature in the range from about 0 to 100C and being with an amount of sulfur trioxide in the range above 0.1 and below about 5 parts for each parts of the feed, adding slaked lime to the treated olefin feed in an amount in the range from about 0.6 to 1.5 mols per mol of sulfur trioxide used in said treatment and bauxite in amount in the range 2 to 10 parts per 100 parts of the feed, said parts being by weight, and separating the resulting mixture by filtration.

2. The process as in claim 1 wherein the amount of sulfur trioxide is in the range from 0.2 to 4 parts, the amount of lime is about 1 mol and the amount of bauxite is in the range 2-4 parts.

3. The process as in claim 1 wherein the treatment is at a temperature in the range from 0 to about 60C.

4. The process as in claim 1 wherein the treatment with the sulfur trioxide is carried out in a falling film reactor at a temperature in the range 30C to 40C.

5. The process as in claim 1 wherein the slaked lime and bauxite have a particle size in the range from about 20 to 200 mesh.

6. The process as in claim 1 wherein said mol fraction of sulfur trioxide in the mixture is in the range from about one-twentieth to one one-hundredth.

7. In the process for the manufacture of an olefin sulfonate, the improvement yielding an olefin sulfonate of improved color which comprises treating a cracked wax olefin feed of the C -C molecular weight range by contacting said feed with a gaseous mixture of sulfur trioxide and air having a mol ratio of 5 to 95, res ectlvely, at a temperature in the range from about 3 to 40C and with about 2 parts of sulfur trioxide per 100 parts of the olefin, adding to the treated olefin about 1 mol of slaked lime per mol of sulfur trioxide used in said treatment and about 3 parts of bauxite per 100 parts of said feed, said parts being by weight, and separating the resulting mixture by filtration.

l I 1F 

1. In the process for the manufacture of an olefin sulfonate, the improvement yielding an olefin sulfonate of improved color which comprises treating a cracked wax olefin feed of the C8-C24 molecular weight range by contacting the feed with a gaseous mixture of sulfur trioxide and an inert diluent, said mixture having a mol fraction of sulfur trioxide which is less than one-fifth and said contacting being at a temperature in the range from about 0* to 100*C and being with an amount of sulfur trioxide in the range above 0.1 and below about 5 parts for each 100 parts of the feed, adding slaked lime to the treated olefin feed in an amount in the range from about 0.6 to 1.5 mols per mol of sulfur trioxide used in said treatment and bauxite in amount in the range 2 to 10 parts per 100 parts of the feed, said parts being by weight, and separating the resulting mixture by filtrAtion.
 2. The process as in claim 1 wherein the amount of sulfur trioxide is in the range from 0.2 to 4 parts, the amount of lime is about 1 mol and the amount of bauxite is in the range 2-4 parts.
 3. The process as in claim 1 wherein the treatment is at a temperature in the range from 0* to about 60*C.
 4. The process as in claim 1 wherein the treatment with the sulfur trioxide is carried out in a falling film reactor at a temperature in the range 30*C to 40*C.
 5. The process as in claim 1 wherein the slaked lime and bauxite have a particle size in the range from about 20 to 200 mesh.
 6. The process as in claim 1 wherein said mol fraction of sulfur trioxide in the mixture is in the range from about one-twentieth to one one-hundredth. 